Fluidic generator

ABSTRACT

A fluidic electric generator having a balanced reed positioned as a rocking member in an air conduit. A spring connected between the reed and the conduit biases the reed in a balanced position. Air flow through the conduit causes the reed to rock at a resonant frequency due to the biasing action of the spring. As the reed rocks, it changes the magnetic reluctance between sets of opposing magnetic poles and causes reversal of flux through the reed thereby inducing an AC signal in surrounding windings. The oscillating reed is oriented in non-impeding relation to the fluidic flow.

United States Patent Apstein [151 3,663,845 1 May 16, 1972 [s 1] FLUIDICGENERATOR [72] inventor: Maurice Apstein, Bethesda, Md.

[73] Assignee: The United States of America as representedbytheSecretaryoftheNevy 22 Filed: Feb. 18, 1971 211 App1.No.: 116,364

..3l0/15, 310/27 ..H02k 35/06 [52] U.S. Cl [51 Int. Cl. [58] Field ofSearch [561 References Cited UNITED STATES PATENTS Morris Pajes....290/4 2.904,707 9/ 1 959 Drescher ..310/15 Primary Examiner-D. X.Sliney Attorney-Harry M. Saragovitz, Edward J. Kelly, Herbert Ber] andSaul Elbaum 57 ABSTRACT A fluidic electric generator having a balancedreed positioned as a rocking member in an air conduit. A springconnected between the reed and the conduit biases the reed in a balancedposition. Air flow through the conduit causes the reed to rock at aresonant frequency due to the biasing action of the spring. As the reedrocks, it changes the magnetic reluctance between sets of opposingmagnetic poles and causes reversal of flux through the reed therebyinducing an AC signal in surrounding windings. The oscillating reed isorientedin non-impeding relation to the fluidic flow.

10 Claims, 3 Drawing figures Patented May 16, 1972 2 Sheets-Sheet 1BRIEF DESCRIPTION OF THE PRIOR ART This invention relates to air drivenelectric generators and more particularly to a small generator that isspecifically adapted for a fast moving projectile wherein the generatoris powered by the relative motion of the projectile through the air.

Air driven generators are well known and early versions of this type ofdevice include a rotatable armature which is driven by a propeller orturbine. The basic operation of the device requires the alternatingreversal of flux from a permanent magnet structure so as to induce an ACsignal in nearby windings. The flux reversal is usually obtained by therotating annature which is fabricated from a ferromagnetic material or apermanent magnet.

Although the air driven generators of the rotatable annature type areable to produce an AC signal, they suffer from two principaldisadvantages. The primary disadvantage is the low voltage regulationcapability of the device. This occurs due to the direct'relationshipbetween generator output and the velocity of the rotatable armature.This problem is quite manifest in the case of projectiles since thesebodies will usually pass through a wide speed range during flight.

A second disadvantage of the earlier air driven generators resides inthe complexity of construction. Because these air driven generatorsinclude rotatable armatures, precision bearings are required. However,even with such bearings, the usable life is very short, due to vibrationat high speeds.

In an attempt to avoid the disadvantages of earlier air drivengenerators, a second generation device, as illustrated in US. Pat. No.2,895,063, has come into existence with constructions employing aflapper reed positioned in a channel through which air flows. In thepresence of air flow, the reed will assume a resonant vibration andwhile vibration occurs, flux generated from a nearby permanent magnetstructure is caused to reverse through the reed. The alternatingdirection of the flux through the reed induces an AC signal insurrounding windings.

This latter discussed air driven generator is a definite improvementover the earlier version. However, due to the location of a reed in thegenerator air conduit, a geometrical situation exists which does notallow relatively free passage of air past the reed. Rather, the reedactsas a flapper valve as it maintains extreme positions duringvibration; As a result, the generator suffers from low efficiency whichresults in relatively low power generation.

BRIEF DESCRIPTION OF THE PRESENT INVENTION The present invention is animprovement over the prior art. In essence the invention utilizes aspring biased reed that vibrates at a resonant frequency so as toalternately vary the direction of flux through surrounding windings. Theunique aspect of the present invention results from the novelgeometrical relationship between the components of the air drivengenerator, namely, a permanent magnet, reed, windings, and air conduit.Due to the particular geometrical relationship between the generatorcomponents there is relatively free passage of air past the reed at thesame time that the air gaps in the magnetic circuit are small. As aresult, the present generator extracts sufficient energy from the airstream to be economically advantageous.

BRIEF DESCRIPTION OF THE DRAWINGS The specific nature of the inventionas well as other objects and advantages thereof, will clearly appearfrom a description of. a preferred embodiment as shown in theaccompanying drawings in which:

FIG. 1 is a perspective, partially sectioned view of the air drivengenerator forming the present invention.

FIG. 2 is a front elevational view of the device shown in FIG. 1.

FIG. 3 is a partial elevational view illustrating the biased connectionof a reed to a leaf spring.

A DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, referencenumeral 10 generally denotes the housing of the air driven generator. Ina typical use of the present invention, the housing 10 and the enclosedcomponents are mounted in a projectile (not shown). Such a projectilewould carry an electric fuze powered by the generator.

The housing 10 comprises several vertically illustrated legs which areferromagnetic. Along one vertical side of the housing are ferromagneticlegs 12 and 14, while ferromagnetic legs 16 and 18 are positioned inrespectively opposite relation.

Pole pieces are arranged along the intermediate length of eachferromagnetic legs. However, each pole piece assumes a particularposition with respect to the other pole pieces as will be explainedhereinafter. To illustrate a particular magnetic configuration,ferromagnetic legs 12 and 14 are shown to include pole pieces 20, 24respectively which are indicated as being north poles. In opposition,ferromagnetic legs 16 and 18 include pole pieces 22 and 26, both beingsouth poles.

The housing 10 further includes permanent magnets 28 and 32 to which theferromagnetic legs l2, l4, l6 and 18 are connected by suitable fasteners30 and 34. The north poles of both permanent magnets 28 and 32 areconnected to ferromagnetic legs 12 and 14 and the south poles areconnected to ferromagnetic legs 16 and 18. It is by virtue of thisarrangement that pole pieces 20 and 24 arenorth poles and pole pieces 22and 26 are south poles.

As shown in FIGS. 1 and 2, the housing 10 forms an open box-like frame.A rectangular non-magnetic conduit is positioned in coaxial inwardlyspaced relation to the frame 10. The conduit is indicated by referencenumeral 36 and functions to channel the flow of air through thegenerator. The conduit intake is denoted by 38. In order to' allow theprojection of the pole pieces, 20, 22, 24, and 26 inwardly through theconduit 36, rectangular apertures 40 are formed at appropriate pointsalong the lateral walls of the conduit 36.

Generator output windings 42 are mounted in outward coaxial relation tothe conduit 36. The windings 42 maintain intimate contacting engagementwith the conduit 36 and are axially positioned between the ferromagneticlegs l4, l8 and l2, 16. The windings 42 are generally rectangularlyshaped and are bounded by mating end plates 44 and 46, although circularand othersuitable shapes may be utilized.

Openings 50 are formed at central points along the lateral walls of theconduit 36. These openings receive the pivot pin supports 52 of aferromagnetic vane or reed 54. The reed rocks about the pivot pins 52 soas to vary its position with respect to the magnetic poles. This willcause the alternatingchange of flux from the magnetic poles, through thereed.

During operation of the device, when the reed 54 assumes the positionshown in FIG. 1, the body of reed 54 lies in coplanar relation with theupwardly tilted north pole piece 20 and south pole piece 26. As will beseen from FIG. 2, only a small air gap 73 is present between the reedand these pole pieces. This results in a magnetic circuit capable ofproviding a low reluctance path for the flux generated by the polepieces 20 and 26. In the position illustrated, the flux lines run in adirection from the north pole piece 20 to the south pole piece 26. Thisinduces a voltage of a first polarity in the windings 42. The directionof flux is reversed as the reed 54 changes its position so as to inducean opposite voltage polarity.

As illustrated in FIGS. 1 and 3, a spring 56 is connected at a lower endthereof to the pivot pin 52 while the upper end is received betweenadjacent spaced pins 58 that extend inwardly from a lateral wall of theconduit 36. The spring 56 biases the reed 54 in such a manner as tocause resonant rocking vibration when air flows through the conduit 36.

Referring to FIG. 3, the horizontal position of reed 54 is indicated byreference numeral 60. When the reed assumes this neutral position, thespring 54 maintains a true vertical orientation. When the reed 54 isangled upwardly as shown in FIG. 1 the leaf spring 56 bows in the leftdirection as indicated by 66 (FIG. 3). When the spring bows this way,the reed 54 is biased downward until it reaches the downward angledposition indicated by reference numeral 68. In this position, the springbows in an opposite direction as indicated by 70. This bowed position ofthe spring will cause the reed 54 to return to the upper extremeposition as shown in FIG. 1 and thereby complete a cycle of vibration.The connection of the spring 56 to the reed 54 establishes a resonantvibration or rocking motion for the reed so long as air rushes throughthe conduit 36.

Returning to FIG. 1, when the reed 54 assumes the tilted position asindicated by 68 in FIG. 3, reed 54 will become disposed in coplanarrelationship with the north pole piece 24 and the south pole piece 22.As in the case of the other pole pieces 20 and 26, the pole pieces 22and 24 are angled so as to achieve coplaner alignment with reed 54.

When reed 54 tilts downward into coplaner alignment with the pole pieces24 and 22, the body of reed 54 moves away from the pole pieces 20 and 26so as to leave a large air gap between the latter pole pieces, which isof sufficiently large reluctance to prevent continued completion of asignificant magnetic circuit between these pole pieces. However, a lowreluctance path now exists between the magnetic pole pieces 22 and 24 soas to cause the completion of a magnetic circuit there between. Flux nowflows between the north pole piece 24 and the south pole piece 22 in areversed magnetic body of reed 54. The flux reversal induces a voltagein the direction through the ferromagnetic body of reed 54. The fluxreversal induces a voltage in the windings 42 of opposite polarity fromthat previously induced. As the reed 54 rocks between the positionsillustrated in FIG. 3, an alternating voltage is produced in the outputwindings 42.

Due to the particular orientation of reed 54 in conduit 36, relativelyfree passage of air past the reed 54 is possible when the reed assumesthe two extreme tilted positions. At these extreme positions, the reedforms small air gaps with corresponding pole pieces so as to produce astrong magnetic circuit. As a result, a relatively high power output ispossible at high efficiency.

Reed oscillators of this type exhibit three important characteristics,namely, they require a minimum airspeed in order for oscillation tostart. This threshold is determined by the spring stiffness. Onceoscillation has started, both frequency and amplitude remain relativelyconstant over a wide range of airspeeds. This combination ofcharacteristics results in increased safety for an airborne weaponsystem because the spring stiffness can be adjusted to require a minimumairspeed to be achieved by the weapon, before generation of power isinitiated. After the generator has started, the constant voltage andfrequency minimize the voltage regulation problem encountered with priorart devices.

I wish it to be understood that I do not desire to be limited to theexact details of construction shown and described, for obviousmodifications can be made by a person skilled in the art.

What is claimed and desired to be secured by U.S. Letters Patent is:

1. A fluid powered generator for producing electrical power comprising:

a. a conduit having a longitudinal axis;

b. at least one pair of magnetic north pole pieces positioned along oneside of said conduit;

c. at least one-pair of magnetic south pole pieces positioned along asecond side of said conduit;

d. ferromagnetic means mounted within said conduit for developingoscillatory motion in response to the passage of fluid through saidconduit such that a low reluctance path is alternatively made betweenone of said pair of north and one of said pair of south pole pieces,whereby the direction of flux lines is alternatively reversed throughsaid ferromagnetic means; and

e. means responsive to said flux reversal for generating an alternatingvoltage.

2. The generator of claim 1 further comprising first and secondpermanent magnets positioned adjacent said conduit so as to impart northand south polarities, respectively, to said north and south pole ieces.

3. The generator 0 claim 1 wherein said means responsive to fluxreversal comprises a plurality of windings having a central axis coaxialwith said longitudinal axis.

4. The structure defined in claim 1 wherein pivot pins integrallyconnected to the member along the rocking axis are supportingly receivedincorresponding openings in the conduit, and resilient means connectedbetween at least one pin and the conduit for biasing the member toward abalanced longitudinal position. v v

5. The structure as claimed in claim 4 wherein the connection ofresilient means to the conduit is achieved by passing an end of theresilient means between adjacent spaced projections extending inwardlyfrom a wall of the conduit.

6. A fluid powered generator for producing electrical power comprising aconduit for channeling fluid therethrough, a ferromagnetic memberdisposed in the conduit for vibrating about a fixed axis as fluid passesthrough the conduit, a permanent magnet, at least one pair of oppositelyfixed magnetic poles disposed in diagonal relation with respect to theferromagnetic member for completing a magnetic circuit between the poleswhen the member assumes a position magnetically bridging the poles, andwindings arranged around the member for generating an alternatingelectrical voltage in response to completion of a magnetic circuit.

7. The structure set forth in claim 6 wherein two pairs of diagonallyspaced opposing magnetic poles are arranged in pairwise angularly offsetrelation so that at opposite extremes of ferromagnetic memberdisplacement, each end portion of the said member comes positionedadjacent a corresponding pole thereby alternatively completing areversing magnetic circuit between each pole pair via the member.

8. The structure defined in claim 7 wherein pivot pins integrallyconnected to the member along the fixed axis of vibration aresupportingly received in corresponding openings in the conduit, andresilient means connected between at least one pin and the conduit forbiasing the member toward a balanced longitudinal position.

9. The structure defined in claim 8 wherein the connection of theresilient means to the conduit is achieved by passing an end of theresilient means between adjacent spaced projections extending inwardlyfrom a wall of the conduit.

10. The structure defined in claim 6 wherein the ferromagnetic body ischaracterized as a rectangular plate symmetrical about the fixed axis ofvibration.

Po-wso UNITED STATES PATENT OFFIQE W CERTIFICATE 0F CORRECTEON PatentNo. 3,663,815 bated 16 May 97 InVentOr(s) APSTEIN, MAURICE It iscertified that error appears in the above-identified patent and thatsaid Letters Patent are hereby corrected as shown below:

Assignee: The United States of America as represented. by the iSecretary of the Amy. I I

I Signed and sealed this Brdday of October 1972.

(SEAL) Attest:

EDWARD M.FLE'I'CHER,JR. I ROBERT GOTT SCHA LK Attesting OfficerCommissioner of Patents UNITED STATES PATENT OFFMIE @ETWECATE @FCORREQ'MGN Patent No. 3,663,816 bated 16 y 1972 Inventor(s) APSTEIN:MAURICE It is certified that error appears in the above-identifiedpatent and that said Letters Patent are hereby corrected as shown below:

Assignee: The United States of America as represented by the Secretaryof the Army. Y

Signed and sealed this 3rd dey of October 1972.

(SEAL) Attest:

EDWARD M.FLETCHER,JR. I ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

1. A fluid powered generator for producing electrical power comprising:a. a conduit having a longitudinal axis; b. at least one pair ofmagnetic north pole pieces positioned along one side of said conduit; c.at least one pair of magnetic south pole pieces positioned along asecond side of said conduit; d. ferromagnetic means mounted within saidconduit for developing oscillatory motion in response to the passage offluid through said conduit such that a low reluctance path isalternatively made between one of said pair of north and one of saidpair of south pole pieces, whereby the direction of flux lines isalternatively reversed through said ferromagnetic means; and e. meansresponsive to said flux reversal for generating an alternating voltage.2. The generator of claim 1 further comprising first and secondpermanent magnets positioned adjacent said conduit so as to impart northand south polarities, respectively, to said north and south pole pieces.3. The generator of claim 1 wherein said means responsive to fluxreversal comprises a plurality of windings having a central axis coaxialwith said longitudinal axis.
 4. The structure defined in claim 1 whereinpivot pins integrally connected to the member along the rocking axis aresupportingly received in corresponding openings in the conduit, andresilient means connected between at least one pin and the conduit forbiasing the member toward a balanced longitudinal position.
 5. Thestructure as claimed in claim 4 wherein the connection of resilientmeans to the conduit is achieved by passing an end of the resilientmeans between adjacent spaced projections extending inwardly from a wallof the conduit.
 6. A fluid powered generator for producing electricalpower comprising a conduit for channeling fluid therethrough, aferromagnetic member disposed in the conduit for vibrating about a fixedaxis as fluid passes through the conduit, a permanent magnet, at leastone pair of oppositely fixed magnetic poles disposed in diagonalrelation with respect to the ferromagnetic member for completing amagnetic circuit between the poles when the member assumes a positionmagnetically bridging the poles, and windings arranged around the memberfor generating an alternating electrical voltage in response tocompletion of a magnetic circuit.
 7. The structure set forth in claim 6wherein two pairs of diagonally spaced opposing magnetic poles arearranged in pairwise angularly offset relation so that at oppositeextremes of ferromagnetic member displacement, each end portion of thesaid member comes positioned adjacent a corresponding pole therebyalternatively completing a reversing magnetic circuit between each polepair via the member.
 8. The structure defined in claim 7 wherein pivotpins integrally connected to the member along the fixed axis ofvibration are supportingly received in corresponding openings in theconduit, and resilient means connected between at least one pin and theconduit for biasing the member toward a balanced longitudinal position.9. The structure defined in claim 8 wherein the connection of theresilient means to the conduit is achieved by passing an end of theresilient means between adjacent spaced projections extending inwardlyfrom a wall of the conduit.
 10. The structure defined in claim 6 whereinthe ferromagnetic body is characterized as a rectangular platesymmetrical about the fixed axis of vibration.